id:A080772 - OEIS Search Results

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Numbers of numbers <= n having prime factors <= k, triangular array read by rows.

+0
1

1, 1, 2, 1, 2, 3, 1, 2, 4, 4, 1, 2, 4, 4, 5, 1, 2, 4, 4, 6, 6, 1, 2, 4, 4, 6, 6, 7, 1, 2, 4, 4, 6, 6, 8, 8, 1, 2, 4, 4, 6, 6, 9, 9, 9, 1, 2, 4, 4, 6, 6, 10, 10, 10, 10, 1, 2, 4, 4, 6, 6, 10, 10, 10, 10, 11, 1, 2, 4, 4, 6, 6, 10, 10, 10, 10, 12, 12, 1, 2, 4, 4, 6, 6, 10, 10, 10, 10, 12, 12, 13, 1, 2, 4, 4 (list; table; graph; listen)

	OFFSET	`1,3`
	COMMENT	`T(n,k) = #{m: 1<=m<=n and p<=k for prime factors of m}.`
	FORMULA	`T(n, n)=n and T(n, k-1) = if k is prime then k-1 else T(n, k), 1<k<=n.`
	EXAMPLE	`Triangle begins:` `................. 1` `............... 1...2` `............. 1...2...3` `........... 1...2...4...4` `......... 1...2...4...4...5` `....... 1...2...4...4...6...6` `..... 1...2...4...4...6...6...7` `... 1...2...4...4...6...6...8...8.`
	CROSSREFS	`Sequence in context: A136311 A126260 A163491 this_sequence A145111 A059250 A104795` `Adjacent sequences: A080769 A080770 A080771 this_sequence A080773 A080774 A080775`
	KEYWORD	`nonn,tabl`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 10 2003`

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Last modified November 30 13:13 EST 2009. Contains 167758 sequences.

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